Construction of a time-resolved multiple resonance spectrometer

我们构建了一个时间分辨多共振光谱仪，配备高功率射频放大器（Kalmus 166LPX1，功率输出：1 kW（脉冲）和200 W（连续波），频率范围：5-86 MHz）和合成器（Anritsu MG250113，频率1-600 MHz）。暂态信号直接输入数字存储示波器（Tektronix 2440, DC-100MHz）和个人计算机（Ricoh PS/V2410NAB）进行数据分析。通过使用x波段脉冲EPR光谱仪（Bruker ESP380E），可以将微波和射频应用于脉冲模式。我们应用该系统测量了激光脉冲辐照产生的瞬态自由基和激发态三态的ENDOR光谱。本研究清楚地表明，该系统在光化学中起着重要的作用，因为光谱分辨率得到了很大的提高。未配对电子自旋的分布可以澄清激发态三态的电子结构和几何形状与基态的偏差。结果表明，光谱灵敏度严重依赖于空腔-螺旋排列。双共振技术与电子自旋回波技术是互补的，即前者对电子自旋与原子核之间的强耦合系统有效，后者对弱耦合系统有效。

We built a time-resolved multiple resonance spectrometer equipping a high power raido frequency amplifier (Kalmus 166LPX1, power output : 1 kW (pulse) and 200 W (CW), frequency range : 5-86 MHz) and a synthesizer (Anritsu MG250113, frequency 1-600 MHz). Transient signals are directly taken into a digital storage oscilloscope (Tektronix 2440, DC-100MHz) and a personal computer (Ricoh PS/V2410NAB for data analysis. Both microwave and radio frequency can be applied in the pulse mode by using an X-band pulsed EPR spectrometer (Bruker ESP380E).We applied the system for the measurements of the ENDOR spectra of transient free radicals and the excited triplet states generated by laser pulse irradiation. The present study clearly shows that this system plays an important role in photochemistry, because the spectral resolution is highly improved. The electronic structure and deviation of the geometry in the excited triplet states from the ground state can be clarified from the distribution of the unpaired electron spins. It was shown that spectral sensitivity severely depends on the cavity-helix arrangement. The double resonance technique is complementary to electron spin echo technique, that is, the former is powerful for the strong coupling system between an electron spin and nucleuses while the latter for weak coupling system.